1. Field
The disclosure relates to a thin film fabricating apparatus and a method of manufacturing an organic light emitting device using the thin film fabricating apparatus.
2. Description of the Related Art
An organic electroluminescent (“EL”) device is a current-driven type of light emitting device in which electrodes are typically disposed on opposing surfaces of a thin film including an organic material, and a voltage is applied between the electrodes to emit light by recombining electrons and holes injected into the organic thin film in both of the opposing electrodes. Thus, applications of such an organic EL device for a light-weight thin display, lighting and the like have been actively researched as the organic EL device may provide high luminescence with a low voltage, may emit light by itself, and may have high visibility.
A conventional method of fabricating an organic thin film mainly used for providing an organic EL device may include a dry process such as vacuum deposition or a wet process such as spin coating. The dry process is a coating process using a relatively low molecular organic material, to effectively control a thickness, to divide a coating area using a mask having an appropriate-sized hole, and to easily provide a structure stacked with organic materials having different characteristics. In the dry process, a multi-layering technique for providing a stacked structure may be effectively used to allow the luminance efficiency and the device life-span to be significantly improved. Thus, the organic EL device may be employed for many applications including a display device. However, in such a technique, vacuum equipment is used, so manufacturing cost in the early state of introducing the equipment or in the maintenance of equipment may be substantially high, and such technique may not be effectively used for manufacturing a large substrate. Thus, a productivity improvement with reduced cost may be restricted.
The wet process may be effectively used for mass production to fabricate a low-priced product since the wet process may be applied for a polymer material having stable physical properties such as high coating properties and heat resistance, the equipment is simplified, and a unique environment such as a vacuum may not be used. However, in the wet process, the solvent for a thin film forming material of an upper layer may be melted and smeared into the organic material of a lower layer to delaminate the lower layer by permeation. Accordingly, the fabricating of a stacked structure using materials having different characteristics, which is an important factor to accomplish high efficiency and a long life-span, as explained above, may not be effectively performed by the wet process. In the wet process, an additive such as a cross-linking hardener may be used to fabricate the stacked structure using materials having different characteristics, but the additive is known for deteriorating the light emitting function. Accordingly, the multi-layering structure having high performance without deteriorating the device function may not be effectively provided by the wet process.
Some proposals using an electro-spray (“ES”) method for fabricating an organic light emitting device have been suggested because the ES method may provide a pattern in a simple way. The ES method includes spraying a solution of a functional material by applying a high voltage between a conductive substrate and a nozzle for emitting the solution to attach the solution onto a substrate. The electrified solution may be changed into fine liquid droplets having a nano-scale by mutual repulsion and dispersion, and the solvent is evaporated by rapidly increasing the surface area to attach only a solute (e.g., organic material) in the solution as a dried state onto the substrate to provide a uniform layer, to stack a plurality of layers.
A plurality of layers may be formed on a substrate in a nano-scale level using the ES method, but generally, the treatment time is substantially long, so the conventionally ES method may not be effectively used for a mass production, and the conventional ES method may have further limitations such as the electrolytic corrosion of parts, the pollution possibility, the maintenance, the lack of practicality, and the like.